1. Field
A positive electrode for a rechargeable lithium battery, a winding element, and a rechargeable lithium battery are disclosed.
2. Description of the Related Art
As information-processing devices such as a mobile phone, a laptop, and the like has recently been down-sized, there is a demand for newly improving characteristics of a rechargeable lithium ion battery as a power source for the information-processing device.
For example, certain technologies improve capacity and cycle characteristics of a rechargeable lithium ion battery by making a positive active material layer having high density. For example, two or more kinds (e.g., more than two kinds) of active material particles having different average particle diameters may be mixed in a predetermined ratio, and simultaneously, carbon black and expanded graphite may be mixed in a predetermined ratio. However, the positive active material layer having high density may not sufficiently improve the characteristics of the rechargeable lithium ion battery.
Accordingly, a technology of making the positive active material layer thicker as well as concurrently (e.g., simultaneously) having high density is suggested. However, when the positive active material layer is made to be thicker after being made to have high density, flexibility of the positive active material layer is deteriorated. Accordingly, damage to the positive electrode may occur when the positive electrode is wound to manufacture a rechargeable lithium ion battery, thereby limiting the thickness of the positive active material layer.
On the other hand, the flexibility of the positive active material layer may be secured by using a low elastic modulus binder, but the low elastic modulus binder may deteriorate cycle characteristics of the rechargeable lithium ion battery. Accordingly, the low elastic modulus binder may be used to make the positive active material layer thicker but hardly improves other characteristics of the rechargeable lithium ion battery.